Datasheet – SMSC USB2512Ai User Manual
Page 22
Industrial Temperature Rated USB 2.0 Hi-Speed 2-Port Hub Controller
Datasheet
Revision 1.97 (08-11-08)
22
SMSC USB2512Ai
DATASHEET
4.2.1.19
Register F8h: Boost_2:0
4.2.1.20
Register FAh: Port Swap
BIT
NUMBER
BIT NAME
DESCRIPTION
7:4
Reserved
Reserved
3:2
BOOST_IOUT_2
USB electrical signaling drive strength Boost Bit for Downstream Port ‘2’.
‘00’ = Normal electrical drive strength = No boost
‘01’ = Elevated electrical drive strength = Low (approximately 4% boost)
‘10’ = Elevated electrical drive strength = Medium (approximately 8% boost)
‘11’ = Elevated electrical drive strength = High (approximately 12% boost)
Note:
“Boost” could result in non-USB Compliant parameters (one
example would be Test J/K levels), OEM should use a ‘00’ value
unless specific implementation issues require additional signal
boosting to correct for degraded USB signalling levels.
1:0
BOOST_IOUT_1
USB electrical signaling drive strength Boost Bit for Downstream Port ‘1’.
‘00’ = Normal electrical drive strength = No boost
‘01’ = Elevated electrical drive strength = Low (approximately 4% boost)
‘10’ = Elevated electrical drive strength = Medium (approximately 8% boost)
‘11’ = Elevated electrical drive strength = High (approximately 12% boost)
Note:
“Boost” could result in non-USB Compliant parameters (one
example would be Test J/K levels), OEM should use a ‘00’ value
unless specific implementation issues require additional signal
boosting to correct for degraded USB signalling levels.
BIT
NUMBER
BIT NAME
DESCRIPTION
7:0
PRTSP
Port Swap: Swaps the Upstream and Downstream USB DP and DM Pins for
ease of board routing to devices and connectors.
‘0’ = USB D+ functionality is associated with the DP pin and D- functionality
is associated with the DM pin.
‘1’ = USB D+ functionality is associated with the DM pin and D- functionality
is associated with the DP pin.
Bit 7= Reserved
Bit 6= Reserved
Bit 5= Reserved
Bit 4= Reserved
Bit 3= Reserved
Bit 2= ‘1’; Port 2 DP/DM is Swapped.
Bit 1= ‘1’: Port 1 DP/DM is Swapped.
Bit 0= ‘1’:Upstream Port DP/DM is Swapped